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CERT(*) Advisory CA-96.27

Original issue date: December 19, 1996

Last Revised: September 24, 1997

              Updated copyright statement



              A complete revision history is at the end of this file.



Topic: Vulnerability in HP Software Installation Programs



- -----------------------------------------------------------------------------



   The text of this advisory was originally released on October 11, 1996, as

   AA-96.04.Vulnerability.in.HP.Software.Installation.Programs, developed by

   AUSCERT. Because of the seriousness of the problem, we are reprinting the

   AUSCERT advisory here with their permission. Only the contact information

   at the end has changed: AUSCERT contact information has been replaced with

   CERT/CC contact information.



   We will update this advisory as we receive additional information.

   Look for it in an "Updates" section at the end of the advisory.



===========================================================================

AA-96.04                        AUSCERT Advisory

               Vulnerability in HP Software Installation Programs

                                 11 October 1996







- ----------------------------------------------------------------------------



AUSCERT has received information that there is a vulnerability in the

Hewlett Packard Software Distributor product, SD-UX, used to install,

update, remove and package HP-UX software and patches.  This software is

installed by default under HP-UX 10.x and may have been specifically

installed as additional software under HP-UX 9.x.  Any system with the

SD-UX package installed is vulnerable.



This vulnerability may allow local users to gain root privileges.



Exploit details involving this vulnerability have been made publicly

available.



Vendor patches are being developed, but until they are made available,

AUSCERT recommends that sites take the actions suggested in Section 3.



- ----------------------------------------------------------------------------



1.  Description



    The HP Software Distributor (SD-UX) is a package that provides a user

    interface which can be used to install, update, remove, and package HP-UX

    software and patches.



    The programs supplied with this package create files in an insecure

    manner.  As these programs execute with root privileges, it is possible

    to create or over-write arbitrary files on the system.  The default

    location of the programs supplied by the package is /usr/sbin.



    To determine if you have SD-UX installed on your system, check for

    the presence of the swinstall (and related) files using the

    following command:



        % ls -l /usr/sbin/sw*



    Individual sites are encouraged to check their systems for the SD-UX

    package, and if installed, take the actions recommended in Section 3.





2.  Impact



    Local users may be able to create or over-write arbitrary files on

    the system.  This can be leveraged to gain root privileges.





3.  Workarounds/Solution



    AUSCERT recommends that sites prevent possible exploitation of this

    vulnerability by taking the measures stated in Section 3.1 immediately.



    If software maintenance is required, AUSCERT advises that sites

    use one of the workarounds given in 3.2, preferably that described in

    Section 3.2.1.



    Vendor patches may also address this vulnerability in the

    future (Section 3.3).



 3.1 Remove permissions



     Until official patches are available sites are encouraged to completely

     prevent the execution of all vulnerable SD-UX programs by any user

     (including root).



         # chmod 400 /usr/sbin/swinstall

         # chmod 400 /usr/sbin/swmodify



     Note that if only the setuid permissions are removed, it is still

     possible for users to gain the privileges of any user executing

     the SD-UX programs (including root).





 3.2 Workarounds



     AUSCERT recommends that if software maintenance is required, sites

     implement one of the following workarounds until official vendor

     patches are made available.



     The workaround described in 3.2.1 is the preferred method of doing

     software maintenance.  If sites are unable to bring their machines

     into single user mode, the workaround given in Section 3.2.2 may be

     more applicable.



 3.2.1  Run in single user mode



     If packages must be installed, the machine should be brought into

     single-user mode, execute permissions re-enabled on

     /usr/sbin/swinstall,



         # chmod 700 /usr/sbin/swinstall

         # chmod 700 /usr/sbin/swmodify



     and all symbolic links in /var/tmp and /tmp removed.  The following

     command can be used to remove the symbolic links:



         # find /tmp /var/tmp -type l -ok rm {} \;



     Once this has been completed, any software package maintenance may be

     safely performed.



     The execute permissions on the vulnerable programs must be removed

     before the machine is brought back into multi-user mode.



         # chmod 400 /usr/sbin/swinstall

         # chmod 400 /usr/sbin/swmodify



 3.2.2 Change temporary file environment variable



     This workaround should only be used if the SD-UX programs must be used

     while the machine is in multi-user mode.



     The SD-UX programs use a number of temporary files.  The location of

     these files can be configured using the environment variable TMPDIR.

     It is possible to set the environment variable TMPDIR to a non-world

     writable directory.  Having the temporary files created in a non-world

     writable directory prevents the exploitation of the vulnerability

     described in this advisory.



     NOTE:  The environment variable must be set in each login

            session BEFORE any SD-UX programs are used.



     To use this method, the following steps must be taken:



     1) As root, create a non-world writable temporary directory for the

     temporary files used by the SD-UX programs.  The location of these

     temporary files can be configured with the TMPDIR environment variable.

     In this workaround, we have chosen to use the directory

     /var/tmp/SD_tmp.



         # mkdir /var/tmp/SD_tmp

         # chmod 700 /var/tmp/SD_tmp



     For this workaround to be effective, sites should ensure that the

     parent directory of $TMPDIR has the sticky bit set if the parent

     directory is world writable.  In this workaround, /var/tmp is the

     directory concerned.  The sticky bit on /var/tmp can be set with the

     command:



         # chmod 1777 /var/tmp





     In all sessions where software maintenance is performed:



     2) Change permissions on the vulnerable programs:



         # chmod 700 /usr/sbin/swinstall

         # chmod 700 /usr/sbin/swmodify



     3) Set the environment variable TMPDIR:



         (under csh)

         # setenv TMPDIR /var/tmp/SD_tmp



         (under sh)

         # TMPDIR=/var/tmp/SD_tmp; export TMPDIR



        and verify that the directory exists and is writable by root.



         # ls -ld $TMPDIR



      4) Perform any software package maintenance.



      5) Remove the execute permissions on the vulnerable programs:



         # chmod 400 /usr/sbin/swinstall

         # chmod 400 /usr/sbin/swmodify



      6) The environment variable TMPDIR is used by many other programs.

      You should either exit this interactive session, or reset the

      TMPDIR environment variables before continuing.



      NOTE:  Steps 2) through 6) must be repeated each time software

             maintenance is performed.



 3.3 Install vendor patches



     Official vendor patches are currently being developed to address the

     vulnerability described in this advisory.  When vendor patches are

     made available, AUSCERT suggests that they be installed.





 ----------------------------------------------------------------------------

 AUSCERT thanks Information Technology Services of the University of Southern

 Queensland, Viviani Paz (The University of Queensland) and Hewlett Packard

 for their assistance in this matter.

 ----------------------------------------------------------------------------



 If you believe that your system has been compromised, contact the CERT

 Coordination Center or your representative in the Forum of Incident

 Response and Security Teams (FIRST).



 We strongly urge you to encrypt any sensitive information you send by email.

 The CERT Coordination Center can support a shared DES key and PGP. Contact

 the CERT staff for more information.



 Location of CERT PGP key

          http://info.cert.org/pub/CERT_PGP.key



 CERT Contact Information

 ------------------------

 Email    cert@cert.org



 Phone    +1 412-268-7090 (24-hour hotline)

                 CERT personnel answer 8:30-5:00 p.m. EST

                 (GMT-5)/EDT(GMT-4), and are on call for

                 emergencies during other hours.



 Fax      +1 412-268-6989



 Postal address

         CERT Coordination Center

         Software Engineering Institute

         Carnegie Mellon University

         Pittsburgh PA 15213-3890

         USA



 CERT publications, information about FIRST representatives, and other

 security-related information are available for anonymous FTP from

         http://www.cert.org/

         http://info.cert.org/pub/



 CERT advisories and bulletins are also posted on the USENET newsgroup

         comp.security.announce



 To be added to our mailing list for CERT advisories and bulletins, send your

 email address to

         cert-advisory-request@cert.org



- ------------------------------------------------------------------------------



Copyright 1996, 1997 Carnegie Mellon University. Conditions for use,

disclaimers, and sponsorship information can be found in

http://www.cert.org/legal_stuff.html and http://ftp.cert.org/pub/legal_stuff .

If you do not have FTP or web access, send mail to cert@cert.org with

"copyright" in the subject line.



CERT is registered in the U.S. Patent and Trademark Office.





This file:

http://info.cert.org/pub/cert_advisories/CA-96.27.hp_sw_install



           http://www.cert.org

               click on "CERT Advisories"



=============================================================================

UPDATES



Hewlett-Packard

===============

  Information concerning patches for the vulnerability described in this

  advisory can be found in HEWLETT-PACKARD SECURITY BULLETIN,

  "Security Vulnerability in swinstall command," Document ID: HPSBUX9707-064



      1)  From your Web browser, access the URL:



          http://us-support.external.hp.com

          (for US,Canada, Asia-Pacific, and Latin-America)



          http://europe-support.external.hp.com  (for Europe)



      2)  On the HP Electronic Support Center main screen, select

          the hyperlink "Support Information Digests".



      3)  On the "Welcome to HP's Support Information Digests" screen,

          under the heading "Register Now", select the appropriate

          hyperlink "Americas and Asia-Pacific", or "Europe".



      4)  On the "New User Registration" screen, fill in the fields for

          the User Information and Password and then select the button

          labeled "Submit New User".



      5)  On the "User ID Assigned" screen, select the hyperlink

          "Support Information Digests".



          ** Note what your assigned user ID and password are for

            future reference.



      6)  You should now be on the "HP Support Information Digests Main"

          screen.  You might want to verify that your email address is

          correct as displayed on the screen.  From this screen, you may

          also view/subscribe to the digests, including the security

          bulletins digest.



      To get a patch matrix of current HP-UX and BLS security patches

      referenced by either Security Bulletin or Platform/OS, click on

      following screens in order:

         Technical Knowledge Database

         Browse Security Bulletins

         Security Bulletins Archive

         HP-UX Security Patch Matrix



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Revision history



Sep. 24, 1997  Updated copyright statement

July 28, 1997, Updates section - added information from Hewlett-Packard.



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